War machines are an important part of many armies in the Warhammer world. Amongst the most spectacular of these engines of destruction are the gigantic cannons of the Empire and Dwarfs, but their manufacture is difficult and the secrets of gun casting and gunpowder manufacture are carefully guarded. Ores and other less sophisticated races build gigantic stone throwers which lob boulders high into the air to come crashing down upon enemy formations or behind city walls. Bolt throwers are powerful giant crossbows that can send a spear-sized bolt clean through several ranks of enemy, skewering each in turn. These are all relatively common war machines that can be found in several armies, and thus their rules are included here.

A war machine comprises the machine plus a crew, which is usually two or three crewmen. The crew are based separately, unlike with the model of a chariot or a ridden monster where the crew or riders are likely to be physically glued to the chariot or mount. This is necessary because a war machine's crew can be forced to flee from their machine, either because they are broken in combat or because they panic. Crew must be kept within 1" of the machine to count as crew.

The machine's crew can wheel, carry or move their machine, perhaps to gain a better position to fire. Note that a war machine may not march or charge.

A player may freely pivot a war machine to face any direction he likes before shooting. Apart from this, a war machine or the crew may not move and fire.

A character model may join a war machine in the same way as he might join a unit of troops. Note however, that war machines never include their own Champions - only units of troops are able to have Champions. The war machine benefits from the associated character's Leadership value in the same way that a unit of troops would.

In the case of war machines, the character must be positioned within 1" of a specific machine for the purpose of allocating damage from shooting hits. However, only crew can operate a machine, a character cannot.

Characters do not actually become crew when they join a war machine and are never hurt should the machine malfunction. They are sensible or experienced enough to keep sufficient distance between themselves and the dangerous mechanism to be safe.